206 (number)

← 205 206 207 →
← 200 210 220 230 240 250 260 270 280 290 → List of numbers — Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	two hundred six
Ordinal	206th (two hundred and sixth)
Factorization	2 × 103
Divisors	1, 2, 103, 206
Roman numeral	CCVI
Binary	110011102
Ternary	211223
Quaternary	30324
Quinary	13115
Senary	5426
Octal	3168
Duodecimal	15212
Hexadecimal	CE16
Vigesimal	A620
Base 36	5Q36

206 (two hundred [and] six) is the natural number following 205 and preceding 207.

In mathematics

206 is both a nontotient and a noncototient.^[1] 206 is an untouchable number.^[2] It is the lowest positive integer (when written in English) to employ all of the vowels once only. The other numbers sharing this property are 230, 250, 260, 602, 640, 5000, 8000, 9000, 80,000 and 90,000.^[3] 206 and 207 form the second pair of consecutive numbers (after 14 and 15) whose sums of divisors are equal.^[4] There are exactly 206 different linear forests on five labeled nodes,^[5] and exactly 206 regular semigroups of order four up to isomorphism and anti-isomorphism.^[6]

In science

There are 206 bones in the typical adult human body.^[7]

See also

• The Year 206 AD
• Cessna 206, a single engine light aircraft
• Bell 206, a light helicopter
• The Peugeot 206, a French supermini automobile
• US Area code 206, and The 206 slang terminology for the urban part of the greater Seattle area
• 206 (Ulster) Battery Royal Artillery (Volunteers) "The Ulster Gunners", part of British Army's 105th Regiment Royal Artillery (Volunteers)
• 206 Hersilia, a fairly large Main belt asteroid
• 206 Bones, a novel by Kathy Reichs

References

1. "Sloane's A058763 : Integers which are neither totient nor cototient", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
2. "Sloane's A005114 : Untouchable numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. 2016-04-18. Retrieved 2016-04-18.
3. "Sloane's A058180 : Numbers whose English names include all five vowels exactly once", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
4. "Sloane's A002961 : Numbers n such that n and n+1 have same sum of divisors", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
5. "Sloane's A011800 : Number of labeled forests of n nodes each component of which is a path", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
6. "Sloane's A001427 : Number of regular semigroups of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator)", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
7. O'Sullivan, Robyn (2006), Your 206 Bones, 32 Teeth, And Other Body Math, National Geographic Science Chapters, National Geographic Books, ISBN 9780792259558.